Biggest rear tire in a 68 Dart?

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flyboy01

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What is the biggest tire I can fit in a stock wheel well of a 1968 Dart assuming I have the perfect backspacing for the tire? I am thinking either 15" or 17" wheels. I don't want to mini-tub it, but may do so later if I have to.

What about a spring relocation kit for the back that Mopar sells? What has to be done, is it a bolt in, or do I have to do some cutting?

I already have a 8 3/4 from a b-body and 5 x 4 1/2 bolt pattern. I will have a custom set of wheels built to fit.
 
I have to replace the tires on my Dart to make it safe to drive, so I thought I might as well get what I want now. Bigger is always better. I an thinking either 255/60 or 275/50's in back maybe 235-60 in front.
 
Anybody here running 275/50R15's in back of a 68 Dart? These are the tires I really want.
 
anything bigger than a 255/60/15 on a 7 1/2 wide B-B rim with 4 1/2" back spacing will be pushing the limit (and maybe beyond).
You will have 1/2 - 3/4" clearnace on the inside from tire sidewall to spring, and maybe 1/2" to the wheel well lip. That all sounds like a lot of clearance until you start going around cloverleafs with 4 people in the car - then it is not.
Mine has 215/65/15s on 6/12 " rims on the front and 255/60/15s on 7 1/2" on the back so the stance is close to being level.
Too wide on the front can lead to front fender interference when turning.
Hope this helps.
 
Thanks, that does help. I guess I will just have to do some careful measuring, because I have gotten a wide variety of opinions on what will fit in the stock wheelwells. as far as clearance, I have run 295's on a Dakota with only 1/4 of clearance to the leafs, I never had a problem with clearance, because the leafs dont shift much in relation to the axle, I am more concerned with the clearance to the body. If at all possible, I want to run 275/50R15 Nitto Drag radials on the back, I was thinking of 225/60R15 on the front.

The car is being trailered here Saturday afternoon, so I can't check until then. Currently the tires are very dryrotted and cracked, so I want to replace them asap so I can drive the car.
 
OK, I just took a bunch of measurements a few days ago. I have a 1968 Dart with an A-body 8 3/4 rear an 10" drums.

12" = Fenderlip to wheelwell at lowest point.
11 1/2" = same as above, but 4 inches higher in the well.
5 7/8" = from Drum surface to leaf spring
5 7/8" = from Drum surface to inner fenderwell
6 1/8" = from drum surface to fender lip

Note, the wheel is pretty much perfectly centered in the wheel well. A 15 x 8" wheel with 4.5 BS is pretty much perfect, just remember that an 8" wheel is actually about 9" wide with the lip, so you end up with about 1 1/2" on either side of the wheel. If you install a 275/60R15 or 275/50R15 tire on it, it will have a total section width of 11", which leaves only about 1/2" on either side of the tire (optimistically).

Wheels that would also work:
15 x 10 = 6.5 BS (very wide, almost no room for sidewall)
15 x 9.5 = 5.75 BS (very wide, almost no room for sidewall)
15 x 9 = 5.5 BS (probably too wide)
15 x 8.5 = 4.75 BS (will give 11" sidewall w/275R60)
15 x 8 = 4.5 BS
15 x 7 = 4.0 BS
15 x 6 = 3.5 BS

My conclusion, you cant go any larger inside the stock wheelwell than 275, moving the spring inboard does not get you any extra room without minitubbing it. The clearance to the spring is not much of a factor, since the axle does not move in realtion to the spring, clearance always stays the same. The wheelwell and fender are a different story. As you drive around, corner, and launch your car at the strip, you will probably rub on the inner wheelwells, you can roll or cut the fender lip back about 1/2" for more clearance on the outside. Another trick is to mount a 275/50R15 on a wheel smaller than recommended like a 15 x 7" wheel, this will suck the sidewalls in and give you another 1/4" of clearance on either side.

Note, these measurements probably will work fine with 16, 17, zand 18" wheels also, just double check the MFG's sidewall dimensions as you can do the the "suck-in" trick with ultra short sidewalls.
 
I'd be interested to know how much backspacing you can use on the front with a 15" steel wheel before you run into clearence problems with the suspension. My 14" wheels with 4" backspacing hit the outer edge of the upper control arms on my '64 Barracuda. I'd think that it might even be a problem with 15" aluminum rims, since they're thicker than steel rims. I'm hoping to eliminate that problem by using 15" steel wheels. Either black or body color, not sure which yet. I've already got the dog dishes. :supz:

Just for general info, I talked to Stockton Wheel yesterday about wheels. They said $135 for stock type steel wheels, 15 x 7, custom offset, sbp, if I supply the wheel centers. My first set of "Mags" cost me $120. Now I gotta pay more than that for 1 steel wheel! Geeeez. :sad5:


:burnout:
 
I think I am going to pick up a set 15 x 7's for my car w/dog-dish caps, I want to paint them body color, I just have to decide what color to paint it.
 
To use the entire wheel well you will need to move the springs with the offset hangers. If not you will hit the leaf springs. The measure ments I took looks like I can go no bigger then 27" tall and 10.5" wide (section width not tread width) using a 15X8" rim with 5" of backspacing. Thats about the size of a 255-60-15.
 
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